you wil get mixed answers i think on this one. i have read that you can have a high humidity during veg. helps with transperation. but during flower you want as little as possible. reason is that the low humidity will increase resin. the resin is there to protect the seeds. in harsh dry climates the plant will make more to protect it seeds (same for sensi which i assume you are doing). so no higher then 50-60% for veg. and not higher then 20% for flower. hope it helps good luck